The first high-profile oral argument of the new Supreme Court term comes Tuesday morning in a campaign finance case officially called McCutcheon v. Federal Election Commission. Across the street, the dispute may come to be known instead as McConnell v. Donation Limits.

Mitch McConnell is guaranteed to make the news almost every day as the Senate minority leader. That’s even been true this fall, when the complexities of his squeezed-on-both-sides campaign for re-election in Kentucky have distracted him from (or prompted him to cede) his customary role as the indispensable dealmaker.

McConnell has been garnering headlines all fall as the leader who isn’t there, on issues starting with Syria and now most prominently on the government shutdown impasse, the future of Obamacare and next week’s prospective debt ceiling collision.

On the issue of regulating money in politics, though, he has remained as steadfastly focused as when he served his freshman term almost three decades ago. He is “the Senate’s most passionate defender of the First Amendment guarantee of unrestricted political speech,” as McConnell told the Supreme Court in asking for rare permission to promote his position before the justices even though he’s not one of the parties in the case.

McConnell has been given 10 minutes of the hour-long argument — a sign the court is seriously entertaining his view that there should be no limits at all on donations to congressional and presidential candidates or to the party organizations that exist to help get them elected.

Anything close to such a landmark ruling would surely stand as one of the biggest triumphs of the senator’s career, whether he survives for a sixth term or not.

It would also herald the biggest change in the campaign finance system at least since the Citizens United case of three years ago. That landmark case struck down limits on independent campaign spending by corporations and unions. Ending donation limits altogether would remove the last big underpinning of campaign finance limits set in the Buckley v. Valeo decision of 1976.

The court said then that campaign spending is generally protected by the First Amendment, but monetary contributions aren’t the same sort of exercises of freedom of speech or association and can be regulated as a way to prevent corruption.

In past cases, Justices Antonin Scalia, Anthony M. Kennedy and Clarence Thomas have all agreed with McConnell that the current distinction is wrong and that contribution limits should be struck down. Chief Justice John G. Roberts Jr. and Justice Samuel A. Alito Jr. have not clearly signaled their thinking.

What McConnell wants goes beyond the aspirations of Shaun McCutcheon, a conservative Alabama businessman, and his fellow plaintiff, the Republican National Committee. They have only asked the court to strike down the federal law limiting the overall amounts any individual may give directly to federal candidates ($48,600) or party committees and political action committees ($74,600) in a two-year election cycle. They argue that there's no genuine threat of funneling co-opting amounts of cash to one politician by laundering the donations through other campaigns or committees. The Obama administration, which is arguing for the FEC, along with other advocates of stricter campaign finance rules, emphatically disagree.

Just as with eliminating those aggregate limits, McConnell’s legal brief (by his longtime sidekick in the cause, Bobby Burchfield) also argues there would be no corrupting influence in lifting the $2,600 cap on the size of a check to an individual candidate before each primary or general election. Advocates for the other side say ending the base limits would make the abuse of money in politics worse than ever, allowing congressional or national candidates to benefit directly from the sort of multimillion-dollar checks that are now flowing routinely to super PACs.

A decision in the case is expected by next spring. However the ruling comes down, McConnell’s role in the case isn't likely to be a wedge issue or the subject of TV attack ads (at least not produced by him) in his campaigns against either Matt Bevin, the businessman running with tea party support in the May 20 GOP primary, or Alison Lundergan Grimes, the Kentucky secretary of state who will be the Democratic candidate in the fall.

Since his third year as a senator, McConnell has become known above all else as the mastermind of a forceful and ceaseless effort to prevent an overhaul of campaign finance law. He cemented his reputation for resilience and hard-knuckled strategizing by sustaining a filibuster of the 1987 bill through eight cloture votes.

He kept his opposition metabolism at full speed for 15 years, until he was finally overpowered and a law was enacted in 2002 banning “soft money” donations to the national parties and regulating the advertising those donations were meant to support. (That defeat for McConnell remains at the root of his notoriously uncomfortable relationship with Arizona’s John McCain, the leading Senate GOP crusader for the law.)

But all that passion and infighting inside the Capitol was minimally noticed in Kentucky, where the senior senator was re-elected with a career-high 65 percent that fall.

There’s little chance he'll poll that high next year, but the judgment of home-state voters will occur regardless of whether the McCutcheon decision becomes the McConnell capstone or his swan song.